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71.
二元稀土催化体系引发的异戊二烯定向聚合 总被引:2,自引:0,他引:2
最早用于共轭双烯烃定向聚合的二元稀土催化体系是LnCl_3-AIR_3,它能引发丁二烯定、向聚合,但催化活性不高。后来,报道了聚合活性较高的氯化稀土催化剂,主要是在二元稀土催化体系中添加适量的醇类试剂。最近,又有新型烷氧基氯化稀土催化 相似文献
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73.
A careful investigation of the telomerization of isoprene with allyl, benzyl, 2-chloroethyl and methyl alcohols on -allylpalladium complex catalysts was carried out. The structures of the obtained telomers were determined by1H NMR spectroscopy. 1-Alkoxy-2,6-dimethyl-2,7-octadiene is a predominant telomer. 2,6-Dimethyloctan-1-ol, which reacts with HCOOH to give (±)-2,6-dimethyloctan-1-ol formate in high yield, was obtained from 1-allyloxy- and 1-benzyloxy-2,6-dimethyl-2,7-octadienes by the removal of allyl and benzyl protective groups and by the hydrogenation of double bonds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1539–1543, August, 1995. 相似文献
74.
Summary Hydrogenations of individual C5 dienic substrates (1,3-cyclopentadiene, isoprene, 1,4-pentadiene, cis-1,3-pentadiene, trans-1,3-pentadiene) and their binary mixtures on a heterogeneous palladium catalyst were studied in cyclohexane at 25°C and 2
MPa. Selectivities of the competitive hydrogenations were determined and the substrates relative adsorption coefficients calculated.
Effects of the diene structure on their reactivity and the stability of the surface complex are discussed. It was found that
differences in selectivity of the competitive hydrogenations of C5 dienes are caused by the difference both in adsorptivity values and in reactivity of adsorbed molecules. The presence of
a five-membered ring in the C5 dienes leads, , in significant reduction of surface complex stability as compared with acyclic structures of C5 dienes. On the other hand, it has a very positive effect on the rate of surface reaction. 相似文献
75.
Ruicheng Ran 《Journal of polymer science. Part A, Polymer chemistry》1993,31(6):1561-1569
A polymer-supported Ziegler–Natta catalyst, polystyrene-TiCl4AlEt2Cl (PS–TiCl4AlEt2Cl), was synthesized by reaction of polystyrene–TiCl4 complex (PS–TiCl4) with AlEt2Cl. This catalyst showed the same, or lightly greater catalytic activity to the unsupported Ziegler–Natta catalyst for polymerization of isoprene. It also has much greater storability, and can be reused and regenerated. Its overall catalytic yield for isoprene polymerization is ca. 20 kg polyisoprene/gTi. The polymerization rate depends on catalyst titanium concentration, mole ratio of Al/Ti, monomer concentration, and temperature. The kinetic equation of this polymerization is: Rp = k[M]0.30[Ti]0.41[Al]1.28, and the apparent activation energy ΔEact = 14.5 kJ/Mol, and the frequency factor Ap = 33 L/(mol s). The mechanism of the isoprene polymerization catalyzed by the polymer-supported catalyst is also described. © 1993 John Wiley & Sons, Inc. 相似文献
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77.
制备了芳基亚胺-脒基稀土二烷基化合物[NNN]Ln(CH2SiMe3)2 {[NNN]=[2-C(H)NDippC6H3NHC(Ph)NDipp], Dipp=2,6-i-Pr2C6H3, Ln=Y (2), Sm (3)}, 2和3通过了1H NMR, 13C NMR, IR和元素分析测试, 通过X-ray确定了化合物2的晶体结构. 加入[Ph3C][B(C6F5)4]和烷基铝, 两个化合物均能高效催化异戊二烯聚合, 具有较好的3,4-选择性(88%), 中等的立体选择性(rr=50%), 较高的分子量(Mn=6.8×104)和较窄的分子量分布(Mw/Mn=1.15). 同时发现, 烷基铝和[Ph3C][B(C6F5)4]的比例影响催化聚合的区域选择性. 相似文献
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79.
Real-time FTIR is a powerful tool to obtain copolymerization reactivity ratios because it allows simultaneous monitoring of individual monomer consumption rates. Based on the Mayo-Lewis equation we showed that in reactivity ratios can be defined as the ratios of apparent rate constants of monomer consumption. The validity and limitations on this new method are discussed in the isobutylene-isoprene and isobutylene-styrene carbocationic copolymerization systems. 相似文献
80.
采用 Nd( naph) 3- Al( C2 H5) 3- ( t- C4 H9) Cl三组分稀土催化剂进行丁二烯 ( BD) -异戊二烯( IP)的顺式共聚合 ,在聚合过程中引入有机氯代烃 ( RCl) ,以与聚合液中的烷基铝作用生成阳离子活性种 ,引发已生成的共聚物的环化反应及单体的环聚反应 ,得到可溶性无凝胶且含有环聚成分的环化共聚合产物 .考察了 RCl用量、单体组成、稀土催化剂用量、反应温度等对原位环化反应的影响 .以红外光谱、核磁共振光谱对环化产物的结构进行了初步分析 ,确认了环化产物的生成 相似文献